The polyphenylene ether resins are a family of engineering thermoplastics that are well known to the polymer art. These polymers may be made by a variety of catalytic and non-catalytic processes from the corresponding phenols or reactive derivatives thereof. By way of illustration, certain of the polyphenylene ethers are disclosed in Hay, U.S. Pat. Nos. 3,306,874 and 3,306,875, and in Stamatoff, U.S. Pat. Nos. 3,257,357 and 3,257,358.
In the prior art, rubber-modified styrene resins have been admixed with polyphenylene ether resins to form compositions that have modified properties. The Cizek patent, U.S. Pat. No. 3,383,435, discloses rubber-modified styrene resin-polyphenylene ether resin compositions wherein the rubber component is of the unsaturated type such as polymers and copolymers of butadiene. The physical properties of these compositions are such that it appears that many of the properties of the styrene resins have been upgraded, while the moldability of the polyphenylene ethers is improved.
It is also known from copending, commonly assigned U.S. patent application Ser. No. 9,791 filed Feb. 6, 1979, that compositions prepared from a polyphenylene ether, a styrene resin and a hydrogenated radial teleblock copolymer of a vinyl aromatic compound and a saturated rubber provide molded articles of improved surface gloss.
Attempts to modify polyphenylene ether alone with radial teleblock copolymers of vinyl aromatic compounds and unsaturated rubber compounds have been unsuccessful because of serious thermal degradation at elevated processing temperatures. This has been overcome in one way by adding a processing aid, such as the mineral oils, phosphate plasticizers, phthalate plasticizers, etc., as generally suggested in Lee, Jr. U.S. Pat. No. 4,077,934. The contents of the foregoing patents and applications are incorporated herein by reference. Such process aids sometimes have a tendency to lower the ultimate physical properties of articles molded from the compositions.
It has now been discovered that selectively hydrogenated radial teleblock copolymers of vinyl aromatic compounds and saturated rubber can be processed with polyphenylene ether to give high impact compositions, without the need to employ styrene resins and/or plasticizing processing aids. The processability of the polyphenylene ether is markedly improved. The new compositions can be modified with conventional additives for thermoplastics, such as pigments, flame-retardants, anti-oxidants, fillers, reinforcements, and the like.